Dados da Submissão

Título

METHODOLOGICAL APPROACH FOR CONTINUOUS MONITORING OF CONCENTRATIONS OF POTENTIALLY TOXIC ELEMENTS (PTEs) AND ANIONS IN SURFACE WATER OF A STREAM NEAR AN IRON MINING WASTE DAM

Texto do resumo

The Gelado Dam was built to contain the rejects (pellet feed) from iron mining in Carajás, Pará State, in the Amazon, Brazil. In this context, the Gelado Project was created to recover rejects to produce pellet feed, with a capacity of 10.6 million tons per year. The installation license was granted in 2010, with operation starting in 2018. Concerns exist about the impact of this operation on the water quality of the Gelado Stream (GS), especially due to the existence of rural human communities living downstream from the dam and using the water from the receiving body (GS) for animal husbandry, irrigation, and fishing. Thus, continuous water quality monitoring is important to assist decision-making regarding environmental disaster prevention. Therefore, the aim of this work is to describe the application of analytical techniques of a system composed of online process analyzers (2045TI and PROCESS IC) for monitoring total phosphorus (P total), Al3+, metals, and anions, as well as the physicochemical parameters of the water quality of GS through submerged sensors and to present the first analytical results obtained after application. The 2045TI process analyzer was programmed for the determination of Al3+, P total, and pH through colorimetry and potentiometry, the PROCESS IC process chromatograph for monitoring potentially toxic metals (Cu, Co, Mn, Cd, Ni), common metals (Li, Na, K, Mg), anions (Cl-, Fl-, NO2-, NO3-), and the three sensors for monitoring Turbidity, Dissolved Oxygen (DO), and Water Conductivity. The system operates continuously and semi-automatically, with stops only for maintenance. The results of the analyses are compiled in real-time via ECU (Electronic Unit Control) through the Modbus protocol. Among the parameters mentioned, all are in compliance with Brazilian legislation for water and effluent quality, CONAMA 357 and CONAMA 430, with the following average concentrations found during the transition period from rainy to dry season in the Amazon region: Cu (0.01 ppm), Co (0.003 ppm), Mn (0.02 ppm), Cd (0.009 ppm), Ni (0.003 ppm), Cl- (2.03 ppm), Fl- (0.02 ppm), NO2- (0.21 ppm), NO3- (0.19 ppm), and during the rainy period: DO (7.01 ppm), Conductivity (48.26 uS/cm), Turbidity (6 NTU), P Total (<0.0001 ppm), Al3+ (<0.0001).

Palavras Chave

WATER QUALITY; MINERATION; INSTRUMENTATION; TOXICOLOGY;